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Biomedical subjects

T Kavanagh

Publications and source records attributed to T Kavanagh.

17 recordsLinked to original sources
PubMed1992

Potato virus X as a vector for gene expression in plants.

The suitability of potato virus X (PVX) as a gene vector in plants was tested by analysis of two viral constructs. In the first, the GUS gene of Escherichia coli was substituted for the viral coat protein gene. In the second, GUS was added into the viral genome coupled to a duplicated copy of the viral promoter for the coat protein mRNA. The viral construct with the substituted coat protein gene accumulated poorly in inoculated protoplasts and failed to spread from the site of infection in plants. These results suggest a role for the viral coat protein in key stages of the viral infection cycle and show that gene replacement constructs are not suitable for the production of PVX-based gene vector. The construct with GUS coupled to the duplicated promoter for coat protein mRNA also accumulated less well in protoplasts than the unmodified PVX, but did infect systemically and directed high level synthesis of GUS in inoculated and systemically infected tissue. Although there was some genome instability in the PVX construct, much of the viral RNA in the systemically infected tissue had retained the foreign gene insertion, especially in infected Nicotiana clevelandii plants. These data point to a general utility of PVX as a vector for unregulated gene expression in plants.

Base Sequence↗
PubMed1992

Exercise training in patients after heart transplantation.

The post-cardiac transplantation patient is frequently debilitated as a result of "end-stage" heart disease and typically demonstrates muscle wasting, with a reduced work capacity, maximum heart rate and peak oxygen uptake. At submaximal effort, perceived exertion and ventilation are higher, and the absolute ventilatory threshold lower, than in normals. A number of published studies have now shown that an exercise rehabilitation programme can induce a good training effect, although possibly not complete restoration of physiological function. The prescription of exercise must take into account the denervated heart's peculiar response to effort, and rely more on perceived exertion and metabolic measurements for defining intensity of training rather than target training heart rates. Changes in mood and personality have also been noted in these patients, and while these may improve spontaneously with the passage of time, there is some evidence that a rehabilitation programme can help in this regard.

Adult↗
PubMed1977

Sexual activity after myocardial infarction.

Questionnaires on sexual activity were completed by 161 patients attending an exercise-centred rehabilitation program an average of some 3 years after a myocardial infarction. In almost half the group, sexual activity was unchanged or increased compared with the period before the infarction. In the remainder it was reduced; this group included 29 men who had adopted a more passive sexual role and 26 who were now having angina or ventricular premature beats during intercourse. Although the patients with diminished activity could not be distinguished by means of formal personality test, questionnaires completed by their wives suggested that they were less willing to assume responsibility, had increased difficulty in adjusting to life at home and at work and were more neurotic and depressed than those with normal or increased activity. Furthermore, those with decreased sexual activity had a poorer response to training in terms of attendance, final average jogging distance and gains in physiologic status. Since the frequency of angina and ventricular premature beats was less during intercourse than during standard laboratory exercise, it was concluded that normal sexual relations carry no special risk for the average postcoronary patient; indeed, by enhancing self-esteem and encouraging effective participation in an exercise programm, acceptance of normal sexual activity may improve the prognosis.

Blood Pressure↗
PubMed1977

Depression following myocardial infarction: the effects of distance running.

A proportion of postcoronary patients seen 16 to 18 months after infarction are seriously depressed (high D score on Minnesota Multiphasic Personality Inventory). A follow-up of 44 such depressed patients showed a significant (p less than 0.001) decrease of standardized D scores, from 80 to 72 units over 4 years of exercise-based rehabilitation. There were associated decreases in scores for hysteria, hypochondriasis, and psychasthenia. A decrease of D score was associated with exercise compliance. An increase of D score was associated with a significant (p less than 0.05) worsening of ST segmental sagging, suggesting that progression of the disease process had contributed to the increase of depression. All of the patients had high (feminine) scores on the masculinity/femininity scale of the MMPI test. This finding was unrelated to the daily running distance or medication; it could represent a "feminine" personality, or be a typical response in a well-educated white collar group. Evidence of successful group interaction may be indicated by reduction in scores for social introversion and schizophrenic traits.

Adult↗
PubMed1977

On the choice of fluid for the hydration of middle-aged marathon runners.

Nine subjects (five well-trained post-coronary patients and four other middle-aged joggers) paticipated in a 42 km "Marathon" race. The course was covered in an average of 212 minutes under pleasantly warm conditions (Maximum 21.7 degree C, 69% relative humidity). Subjects were given initial hyperhydration and repeated subsequent doses of water, "Erg" (Na+ 19mE/l K+ 10.7mE/l, glucose 5.3g/100 ml) or a "Special Solution" (during the race Na+ 21mE/1 glucose 4.1g/100 ml; after the race Na+ 20 mE/l, K+ 4.7mE/l., glucose 4.1 g/100 ml). Weight loss averaged 2.2 kg and sweat production 3.3l taking account of water liberated from the hydration of glycogen and the oxidation of food stuffs, it was estimated that most subjects suffered relatively little dehydration over the race (0.4--0.8l). This was confirmed by a sustained urine production of greater than 100ml/hr. Nevertheless, rectal temperatures showed substantial elevation over the race (final readings 38.3 - 40.2 degree C). In terms of fluid balance and stability of plasma mineral composition, the runners drinking water performed slightly better than those receiving the other two solutions. Nevertheless, there may be merit in giving potassium solutions during recovery from vigorous effort.

Adult↗
PubMed1976

Maximum exercise tests on "postcoronary" patients.

The maximum oxygen intake has been measured directly (uphill treadmill walking) in 36 patients following recovery from myocardial infarction. These were selected as follows: 15 consecutive new entrants to an exercise program that is currently accepting about one-sixth of the total reported myocardial infarction hospital admissions in metropolitan Toronto (group A), 12 patients not responding well to training (group B), and 9 patients now running substantial distances (group C). The only clinical complications were two episodes of ventricular tachycardia. Twenty patients reached an oxygen plateau, and in group C, the maximum heart rate (170/min) reached Scandinavian norms, with a maximum oxygen intake (2.63 +/- 0.35 1/min STPD, 36.9 +/- 4.8 ml/kg-min STPD) as in healthy men of the same age. The rate of adaptation to a progressive submaximum test was such that comparable Astrand nomogram predictions of VO2max were obtained from data in the 3rd and 5th min at the third load. Predictions generally agreed closely with directly measured values. It may be concluded that in patients who have recovered sufficiently to enter an exercise rehabilitation program 1) predictions of VO2max have about the same accuracy (+/-10) as in healthy subjects, and 2) direct measurements can often be pursued to an "oxygen plateau" without due risk.

Adult↗
PubMed1975

Depression after myocardial infarction.

The Minnesota Multiphasic Personality Inventory was completed by 101 patients 16 to 18 months after a proved myocardial infarction. The data suggested a bimodal distribution of patients. One class of patients had a relatively "normal" personality score apart from a tendency to hypomania. The second class had severe depression, with associated hysteria, hypochondriasis and psychasthenia. The severely depressed patients were older, with a greater tendency to hypertension and angina, and a tendency to smaller gains in aerobic power despite an equal intensity of endurance training. The distinction between "normal" and "depressed" postinfarction patients seems of some clinical importance, for the two classes of patients require opposite supportive techniques--restraint and encouragement, respectively.

Age Factors↗
PubMed1975

A controlled prospective study of the effect of endurance training on the recurrence rate of myocardial infarction. A description of the experimental design.

A multicenter prospective study has been designed to determine whether participation in an exercise program which produces a significant training effect will affect the recurrence rate in men who have survived an initial myocardial infarction. The control group consists of subjects who participate in a program involving low intensity activities designed to avoid a significant training effect. The subjects will be followed for a period of 4 years and a reduction of 50 per cent in the risk of recurrence will be considered clinically significant. The criteria for entry, the method of allocation, the structure of the exercise program and method of assessing cardiorespiratory fitness are described.

Angina Pectoris↗
PubMed1975

Conditioning of postcoronary patients: comparison of continuous and interval training.

Interval training is theoretically attractive as a means of training the postcoronary patient, since by appropriate choice of exercise and recovery intervals substantial cardiac training can be achieved without the accumulation of anaerobic metabolities and associated increases of blood pressure and cardiac work load. Six patients with frequent exercise-induced anginal attacks coped well with a program based upon running or jogging (1/2 to 1 minute) followed by 1 to 1-1/2 minutes of slow walking. Despite a poor previous response to several months of continuous training, they showed a substantial gain of aerobic power with one year on the interval regimen. The ST segmental response to a fixed increment of pulse rate remained unimproved, but probably because of the enhanced cardiorespiratory fitness, the ST depression at a fixed work load was lessended. Twenty other patients who had also followed a continuous exercise regimen for up to one year were switched to interval-type work. Over the next year they failed to progress as fast as a group of 15 patientswho persisted with continuous effort training. While interval work is helpful to the severely disabled anginal patient, it apparently leads to slower progress in the average postcoronary patient.

Adult↗